Pneumocystis carinii pneumonia is an opportunistic infection that is common in immunosuppressed patients, including those receiving immunosuppressive therapy for inflammatory diseases. Wegener's granulomatosis is a rare disease characterized by the clinicopathologic features of upper and lower airway disease and renal disease demonstrating necrotizing granulomatous inflammation on histopathology. Immunosuppressive agents are a cornerstone of therapy for patients with Wegener's; combination therapy with glucocorticoids and cyclophosphamide leads to marked improvement in over 90% and complete remission in 75% of patients. Of 158 patients with Wegener's granulomatosis studied at NIH, there have been 11 episodes of Pneumocystis carinii pneumonia. The purpose of this retrospective review of these 11 cases is to analyze the incidence of disease, the risk factors in this patient population, their clinical characteristics, and the treatment and outcome in these patients. Data have been analyzed and a manuscript has been submitted to the American Journal of Respiratory and Critical Care Medicine.